Why Is My Signal Booster Not Working?

You have just installed your Cel-Fi system but you do not see any more bars on your mobile device. According to the bars on your handset you are not getting better signal after installing your Cel-Fi Booster Device.

Even if your Cel-Fi is installed correctly and the service you experience is substantially improved, your handset may not show these improvements with higher signal bars.

The easiest way to confirm that the Cel-Fi is working is to remember what your initial need was. For example, if you had no coverage in this area before and now you do, or if you were experiencing dropped calls before and now you are able to hold calls without an issue, you can say without a doubt that your handset is getting a better signal thanks to your Cel-Fi Smart Signal Booster!

The simple truth is that the number of bars might not always change. The bars on your handset or tablet can be confusing as they do not always show raw signal strength, as one might expect. Almost all mobile manufactures have their own algorithm to calculate things like signal strength, signal-to-noise ratio, and channel loading among other things.

Troubleshooting my Signal Booster

Novotech and Cel-fi have created this handy page to help you troubleshoot the most common issues after a signal booster is installed including:

  1. Slow data speeds
  2. Spotty or inconsistent coverage
  3. Dropped calls


Watch this video for clarification on bar signal strength.



Scroll below for instructions on how to check raw signal strength from an iPhone or Andriod device.

How to Determine your Signal Strength


iOS 10.3.1 and newer


  1. Dial *3001#12345#*
  2. Select “LTE”
  3. Select “Serving Cell Meas” signal strength will be displayed as “RSRP0”


  1. Dial *3001#12345#*
  2. Select “UMTS”
  3. Select “Serving Cell Meas” signal strenght will be displayed as “RSCP0”

iOS versions OLDER than 10.3.1

  1. Dial *3001#12345#*
  2. Hold the Power/Lock button until you see “Slide to power off”. Do not power off, but release the power button.
  3. Hold the Home button until the phone goes back to your home screen. At this time you should now see your raw signal strength instead of bars on the top left of your handset.
  4. To go back to bars, dial *3001#12345#* and tap the home button to Exit Field Test Mode.


Most Android Devices

  1. Go to Apps
  2. Settings
  3. General
  4. About Device
  5. Status
  6. You will find Signal Strength on this screen


  1. Dial *#0011#
  2. The Signal Indicator will be displayed as RI or RSRP.

Samsung RI RSSP

Deciphering what RAW Signal Strength means to you

The raw signal strength can determine if your handset is getting signal from the Coverage Unit. With the Coverage Unit plugged in, go to the location of your CU and dial the Field Test Mode Code for your phone, remember this number. Now unplug your Coverage Unit and watch your signal strength change, it may take a few minutes for your phone’s readings to update. Keep in mind, a smaller the negative number equals stronger signal. For example, if your signal strength jumps from -111 to -100 your signal is 10 times stronger with Cel-Fi than it was without Cel-Fi.

While the number changes might seem slight, even 3 numbers lower is 2 times stronger than before. The cellular scale is not 0 to 100, but the range of usable cellular LTE signal is -120 (just barely usable) to -60 (about the best you will find). Here is a simple chart to give you an idea of just how BIG the “little” improvement really is.

  • How much stronger the signal really is
  • Improvement in handset’s signal value in dB (with Cel-Fi CU on)

Support & Warranty

We provide pre and post-sales consultation for Cel-Fi device set-up and installation. We partner with some of the top installation companies globally to source installation for your device. Novotech is committed to providing superior customer service when it comes to your cel-fi device. We have over 20 years of experience in support and can help you solve your issue quickly and efficiently. If you're still having issues with your signal booster, please contact us for help. You can see support and warranty information here.